docs: def _get_dtype_maps():
      """ Get dictionaries to map numpy data types to ITK types and the 
      other way around.
      """
      
      # Define pairs
      tmp = [ (np.float32, 'MET_FLOAT'),  (np.float64, 'MET_DOUBLE'),
              (np.uint8, 'MET_UCHAR'),    (np.int8, 'MET_CHAR'),
              (np.uint16, 'MET_USHORT'),  (np.int16, 'MET_SHORT'),
              (np.uint32, 'MET_UINT'),    (np.int32, 'MET_INT'),
              (np.uint64, 'MET_ULONG'),   (np.int64, 'MET_LONG') ]
      
      # Create dictionaries
      map1, map2 = {}, {}
      for np_type, itk_type in tmp:
          map1[np_type.__name__] = itk_type
          map2[itk_type] = np_type.__name__
      
      # Done
      return map1, map2